Fire Life

Cardiac Health: Looking for Puzzle Pieces That Fit

By Mary Jane Dittmar

Photo courtesy of www.photos8.com

 

That there may be a connection between air pollution and sudden cardiac death is not news. What is news, however, is that at least one study has found that “pollution-related cardiac arrests occurred when particulate levels were high but still below the current Environmental Protection Agency (EPA) safety threshold of 35 micrograms per cubic meter of air,” according to a study published in the September 20 online American Journal of Epidemiology. The research was conducted by the North Shore-Long Island Jewish Health System. In a previous column, for example, it was reported that exposure to ultrafine particles during fire suppression should be considered a potential contributing factor for coronary heart disease in firefighters. The study was published in the Journal of Occupational and Environmental Medicine, Aug. 2010.

The North Shore-Long Island Jewish Health System study looked at more than 8,000 people who suffered out-of-hospital cardiac arrests in New York City between 2002 and 2006 in relation to air pollution levels during that time. The number of out-of-hospital cardiac arrests rose four to 10 percent with each 10 microgram per cubic meter of air increase in small-particle air pollution. The eye-opening finding here, as cited above, was that these cardiac arrests occurred when particulate levels were still below the EPA safety threshold. This study adds to the growing body of research that suggests air pollution is bad for the heart. Earlier this year, the American Heart Association issued a statement noting that evidence is growing that air pollution is a risk factor in heart attack, stroke, and cardiovascular death.

The National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health, has funded a number of studies on the association between airborne particles, such as sulfur dioxide and other fossil fuel emissions, and the risk of early death from cardiovascular disease. The studies found a strong relationship. One of these studies was the Six Cities Study, conducted in 1974, at Harvard University. It initiated a long-term study on residents of the cities to assess the effects of common air pollutants on respiratory and cardiovascular health. More than 8,000 subjects were studied over a period of 14 to 16 years. The focus was on the health effects of gaseous pollutants, such as sulfur dioxide (the result of coal burning), and fine particle air pollution (that comes from motor vehicle exhaust and power plant emissions). Subjects living in the more polluted cities were found to have a higher risk of hospitalization and early death from pulmonary and heart diseases as compared with those living in the less polluted cities. Fine particle pollution was proven to have a stronger association with mortality than the gaseous pollutants.

In a NIEHS-American Cancer Society-sponsored follow-up study, the cardiovascular effects of fine particle air pollution was assessed in a sample of more than 500,000 people in 50 cities. A strong association between high concentrations of fine particle pollution and increased mortality from cardiopulmonary illness was confirmed. More recent studies have shown that particles less than 2.5 microns in diameter—about 30 times smaller than the width of a human hair—are more harmful to lung tissue than the larger particles.
The ultimate goal of NIEHS-sponsored research on air pollution is to provide regulatory agencies with the scientific data that will enable them to develop national air quality standards that adequately protect the health of U.S. citizens.

Advocacy Note: This sounds promising, but these problems are not always resolved in the favor of humans’ health and well-being. That’s the reason the column brings up “Personal Health Advocacy” often and is calling for a viable voice from the fire service to get our legislators to make human health the overriding concern and issue in these situations. Pick up a newspaper or listen to a news broadcast, and you will find one or more of our “enlightened” legislators calling for silencing the voice of the EPA when it calls for more stringent control of the air we breathe and the water we drink. It has become politically fashionable today to put costs above everything and anything (except for refunding politicians’ election campaigns). They cite the costs of improving air and water quality but never take into account the costs of not doing so. Health costs have been escalating; more people have been diagnosed with pulmonary problems and cardiovascular problems. We cannot take down the cost of healthcare unless we eradicate some of the triggers that are causing the health problems themselves. We are not even addressing the human misery these policies create or other costs such as time lost from work and diminished contributions to communities.

Effects of Environmental Exposures on the Development of Heart Disease

According to Patrick Mastin, Ph.D., acting deputy director of the NIEHS Division of Extramural Research American, the Recovery and Reinvestment Act of 2009 (ARRA) makes available funds to expand its support of research to determine which exposures are most dangerous and how they impact human health. He notes: “Evidence indicating a link between exposure to environmental agents, like air pollution and metals, and the development of cardiovascular disease has continued to grow over the last 15 years.” 
Results from NIEHS-funded studies have demonstrated, once again, a strong relationship between levels of airborne particles, sulfur dioxide, and other fossil fuel emissions and risk of early death from heart disease. In addition, research has shown that exposure to environmental agents, such as dioxins (http://www.niehs.nih.gov/health/topics/agents/dioxins/index.cfm) and pesticides (http://www.niehs.nih.gov/health/topics/agents/pesticides/index.cfm), can contribute to cardiovascular defects.

Among the areas researchers are studying under the Recovery Act are the impact of air pollution on artery hardening in college students,  the relationship between pesticide exposure and cardiovascular disease;  “Clock genes”, environmental challenges, and cardiopulmonary disease  (does the interaction between altered circadian genes and light pollution increase the progression of cardiopulmonary disease in shift workers?); linkages between air pollution and stroke; and how DNA movement and environmental exposures contribute to the hardening of arteries.

New Possible Risk Factor for Heart Disease?

Abnormal heart rate turbulence (how smoothly the heart rate returns to normal after a premature ventricular contraction) is associated with an increased risk of death from heart disease in older individuals who are otherwise considered at low risk for heart disease, according to a study funded by the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health. This study appears in the Journal of Cardiovascular Electrophysiology. (February 15).

The study followed 1,272 adults aged 65 and older for about a 14-year period. The study found that subjects considered at low risk for heart disease when rated by the traditional risk factors (age, gender, high blood cholesterol, high blood pressure, diabetes, obesity, and smoking) on average were eight to nine times more likely to die of heart disease if they had abnormal heart rate turbulence values than low-risk subjects who had elevated levels of C-reactive protein (CRP), a potential heart disease biomarker. The latter were about 2.5 times more likely to die than those with normal or low CRP. 

It is not known yet if abnormal heart rate turbulence can be treated or prevented, but researchers say that findings like these may stimulate interest within the medical community in measuring heart rate turbulence in clinical practice; this type of measurement is not widely available now. 

Robin Boineau, M.D., a medical officer in the NHLBI’s Division of Cardiovascular Sciences, sees this study as a possible opportunity to prevent disease as well as predict it, since “it appears that signs of heart rate turbulence are also generally present a year or more before clinical manifestations of heart disease.” 

For additional information, see “Cardiovascular Health Study (CHS)” at <https://biolincc.nhlbi.nih.gov/studies/chs/> and “What Are Heart Disease Risk Factors?” at <http://www.nhlbi.nih.gov/health/dci/Diseases/hd/hd_whatare.html> The NIH News Release is available online at <http://www.nih.gov/news/health/feb2011/nhlbi-15.htm>.

Food for Thought: Keep on the Move. More and more studies have indicated that it is more important to be “fit” than to be the ideal weight. We are not talking about obesity, which is a risk factor for many illnesses, but about being mildly overweight. Moving about whenever you can helps to keep you alive, and lack of exercise puts you at a greater risk for mortality than being slightly overweight, some studies have noted.

Make Your Voice Heard: NIOSH Seeks Comment on Emergency Responder Health Monitoring Draft. The National Institute for Occupational Safety and Health’s (NIOSH)  “Emergency Responder Health Monitoring and Surveillance” system proposes a new framework for ensuring responder safety and health by monitoring and conducting surveillance of their health and safety during the entire cycle of emergency response, including the predeployment, deployment, and postdeployment phases of a response, according to NIOSH. The system includes a guidance section describing principles involved in ensuring optimal responder safety and health and tools that can be used to facilitate the execution of their principles during a response. The draft document is available at http://www.cdc.gov/niosh/docket/review/docket223/. Written public comment will be accepted until April 4, 2011.

A consortium of federal agencies, state health departments, and volunteer organizations, headed by NIOSH, drafted the document. When finalized, it is expected to serve as an interagency resource intended for preview and possible publication by the National Response Team. “The gap in our ability to ensure the safety and health of all workers involved in large-scale and complex emergency responses has been documented through our responses to the World Trade Center disaster, Hurricane Katrina, and the Deepwater Horizon Oil Spill,” according to NIOSH Director John Howard, M.D. “This document is the result of our shared learning from these events and our combined commitment to protect those workers who respond in times of need.”

REMINDER: Be mindful of the risks and dangers posed by the weather. Cold winds, low temperatures, snow, and overexertion can tax the heart. One news item reported that four men died while or immediately after shoveling snow in the Chicago, Illinois, area during the record-making February snowstorms. Although these men were in their 60s, even younger hearts can be affected by such weather and overexertion conditions. Make sure you are in good physical condition (when’s the last time you had a physical and heart evaluation or stress test?) and then use moderation in shoveling snow and other activities in the wintery weather. Don’t get overtired, alternate work intervals with rest periods, stop immediately if you experience shortness of breath or chest pain, and call 911 if you think something is not “right.” It is better to call and find that you do not have a serious problem than not to call and then experience a problem.